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Horváth Gábor

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Horváth Gábor
Experimental study of the functions of zebra stripes: A new thermophysiological explanation

Aug 31 - csütörtök

09:30 – 09:50

Bioenergetika és fotobiofizika

E37

Experimental Study of the Functions of Zebra Stripes: A New Thermophysiological Explanation

Gábor Horváth

Department of Biological Physics, Physical and Astronomical Institute, Faculty of Natural Sciences, Eötvös Loránd University, H-1117 Budapest, Pázmány sétány 1, gh@arago.elte.hu

With a thermodynamic field experiment we refuted the wide-spread hypothesis of the cooling effect of zebra stripes. Using Schlieren optics in laboratory, we showed that convective air eddies do not form above sunlit zebra stripes that could cool the zebra’s body. In field experiments we demonstrated that female horseflies prefer to suck blood on sunlit dark (warm) and shiny (strongly polarizing) host animals. In field experiments we showed that the escape success of horseflies decreases with decreasing target temperature, that is escape success is driven by temperature. This explains the behaviour of biting horseflies that they prefer warmer hosts against colder ones. Our results also explain why horseflies prefer sunlit dark hosts against bright ones, and why these parasites attack their hosts usually in sunshine, rather than under shaded conditions. In field experiments we corroborated our new hypothesis explaining why biting horseflies avoid host animals with striped pelages: Since the temperature gradients at the borderlines of sunlit white and black stripes can hamper the thermal vessel detection by blood-seeking female horseflies, striped host animals are unattractive to these parasites which prefer hosts with homogeneous coat, on which the temperature gradients above blood vessels can be detected more easily. This 5-year research project was supported by the grant NKFIH K-123930 received from the National Research, Development and Innovation Office.